Epistasis between mutations can make adaptation contingent on evolutionary history. Yet despite widespread ‘microscopic’ epistasis the involved, microbial evolution experiments show consistent patterns of fitness increase replicate lines. Recent work shows that this consistency is driven in part by global diminishing-returns and increasing-costs epistasis, which systematically less beneficial (...

Epistasis occurs when the effect of a mutation depends on its carrier's genetic background. Despite increasing evidence that epistasis for fitness is common, role during evolution contentious. Fitness landscapes, which are mappings genotype or phenotype to fitness, capture full extent and complexity epistasis. landscape theory has shown how affects course outcome evolution. Moreover, by measuri...

A new framework to formulate and quantify the epistasis of a problem is proposed. It is based on Shannon’s information theory. With the framework, we suggest three epistasis-related measures: gene significance, gene epistasis, and problem epistasis. The measures are believed to be helpful to investigate both the individual epistasis of a gene group and the overall epistasis that a problem has. ...

Epistasis effects (gene interactions) have been increasingly recognized as important genetic factors underlying complex traits. The existence of a large number of single nucleotide polymorphisms (SNPs) provides opportunities and challenges to screen DNA variations affecting complex traits using a candidate gene analysis. In this article, four types of epistasis effects of two candidate gene SNP...

We present a new parameterization of physiological epistasis that allows the measurement of epistasis separate from its effects on the interaction (epistatic) genetic variance component. Epistasis is the deviation of two-locus genotypic values from the sum of the contributing single-locus genotypic values. This parameterization leads to statistical tests for epistasis given estimates of two-loc...

Mao Y, London NR, Ma L, Dvorkin D, Da Y. Detection of SNP epistasis effects of quantitative traits using an extended Kempthorne model. Physiol Genomics 28: 46–52, 2006. First published August 29, 2006; doi:10.1152/physiolgenomics.00096.2006.—Epistasis effects (gene interactions) have been increasingly recognized as important genetic factors underlying complex traits. The existence of a large nu...

Epistasis, a term coined by William Bateson in 1909 [1], refers to the interdependence of mutations in their phenotypic effects. Let the phenotypic value of a trait relative to that of the wild type be fA and fB for mutants A and B, respectively, and let the phenotypic value of the corresponding double mutant be fAB. Although variation exists, epistasis is usually defined by ε = fAB − fAfB and ...

We investigate the multilinear epistatic model under mutation-limited directional selection. We confirm previous results that only directional epistasis, in which genes on average reinforce or diminish each other's effects, contribute to the initial evolution of mutational effects. Thus, either canalization or decanalization can occur under directional selection, depending on whether positive o...

High-order epistasis-where the effect of a mutation is determined by interactions with two or more other mutations-makes small, but detectable, contributions to genotype-fitness maps. While epistasis between pairs of mutations is known to be an important determinant of evolutionary trajectories, the evolutionary consequences of high-order epistasis remain poorly understood. To determine the eff...